Waste water that is generated in various industrial processes is commonly loaded with multifarious inorganic species such as Na+, Ca++ and Cl− that preclude its applicability in different downstream purposes. Therefore, removal of inorganic contaminants from the waste water becomes imperative before using the same for recycling purposes.
Conventionally, inorganic contaminant removal has been achieved by the lime-softening process. The process involves use of diverse chemicals such as lime, soda ash, dolomite, ferric chloride and anionic polyelectrolyte that makes the process labor intensive, complex, expensive and thus, prohibitive. The optimization of such diverse chemistries is a very challenging task. Further, in procuring lime from multiple sources, its quality may vary which may lead to sub-optimal precipitation of inorganic contaminants. Even further, high levels of scale forming inorganic contaminants such as Ca2+, Mg2+ and SiO2 may be carried over to the downstream unit operations such as reverse osmosis (RO) which in turn may result in poor recovery and heavy solid waste (sludge) production.
Use of a variety of chemicals and processes for the decontamination of waste water is known. For example, U.S. Pat. No. 5,611,934 discloses a process for decontaminating dye containing effluents in order to render it suitable for discharge into lagoons or sewers. The process of U.S. Pat. No. 5,611,934 is, however, useful only for removing the coloring principles from the waste water. Similarly, U.S. Pat. No. 3,408,293 discloses a purification process which is specific towards the removal of coal fines and clay from water released by coal preparation plants. However, the specificity of application of the afore-stated processes limits its universal use. Further, use of a host of different varieties of chemicals in the decontamination process increases its complexity along with making the process labor intensive and expensive. Therefore, there a need for an effective process for the decontamination of waste water that reduces the drawbacks associated with prior art processes.